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Watershed Functioning, Plant Ecology and Stream Processes

Tying it All Together

with Gina and Tom McCoy

Saturday, July 20, 2013

Two highly qualified stream experts lead one of OHA's 2013 summertime Highland Wonders field trips, offering a unique opportunity to learn about our highland waterways.



First, an indoor presentation about our local streams was provided to the community at the Chesaw Community Center.

Directly afterward, a field trip was offered, providing on-the-ground examples of the concepts discussed during the presentation. The group talked through a Riparian-Wetland Functional Checklist that drew our attention to various hydrology, vegetation and erosion/deposition characteristics of Myers Creek.


Gina McCoy, Stream Morphologist, discussed how watershed functioning leads to characteristic patterns of streamflow and sediment delivery, creating the watershed ‘signature’. She also explained how the resulting interactions among energy, water, sediment and structural elements in streams create the morphology we can see. 

Tom McCoy, Plant Ecologist, discussed how disturbance ecology shapes the upland and riparian plant communities, contributing significantly to the characteristic watershed 'signature' and fluvial processes.


Tom helped the group read the history of the wetland through observing signs in the soil and vegetation. Regarding the above sample, he said, "See the little cellular marks? Those are essentially oxygen snorkels, down to the roots. So what's happening is in the rhizosphere it's excreting oxygen and oxidizing right around the root itself... and that's what those little stripes are that you're seeing in the soil. That's telling us that at one time, there was a very high water table, slow moving, beaver pond perhaps... something like that... and now that's not present."


Gina describes the connections between the big picture and the close-up view: "Dialing down from the landscape to the site scale: watershed functioning is driven by interactions between non-living and living elements; stream processes are driven by watershed functioning; and stream channels respond dynamically to both local influences and the integration of processes occurring across the watershed."

Tom adds his perspective on the role of plant life: "Riparian vegetation is a highly diagnostic attribute of the landscape. It can often be read like a book that describes the infinitely variable interaction between soil, climate, vegetation, channel characteristics, and past and present disturbance and land use patterns."

Gina explained how the term "bankfull" can be understood in an incised channel such as Myers Creek north of Chesaw. "When you have an oversized channel that doesn't have that floodplain anymore... bankfull becomes this thing that happens inside the active channel. Basically the edge of the perennial vegetation is your indicator instead of the edge of the bank. That's what stays scoured out and carries those medium/high flows."
Questions were answered about sediment capture, comparing the ability of reed canarygrass vs. sedges to capture sediment. Tom explained that reed canarygrass lays flat under the stream currents with very low capacity for capturing sediment, whereas sedges are fairly robust vertical plants that can capture more sediment. 
The group observed the bank erosion that is occurring, and Gina explained the erosion as a necessary stage that the stream needs to go through as it seeks equilibrium.


Gina McCoy spent her childhood as an amphibian exploring the outdoors and water bodies of New Zealand. She has resided in the Northwest since the early 80’s. She attended graduate school at Oregon State University in 1990 where she studied forest hydrology and landscape ecology with the aim of developing an understanding of the interplay between the physical and biotic components of watershed functioning and stream processes. Gina has been a habitat engineer with the Washington Department of Fish Wildlife since 2001. Specializing in stream processes, she provides technical assistance for stream-related activities such as stream and riparian restoration, bank stabilization, flood hazard mitigation and fish screening and passage. Prior to her service with WDFW she worked as a hydrologist for the Yakama Nation, initiating and managing a large scale watershed restoration project. Gina now resides in the Methow Valley with way too many animals and a patient husband.

Thank you, Gina and Tom McCoy, for providing such an informative and interesting learning experience!